In amateur photography, most film processing is accomplished in large, automatic batch-processing labs to help hold down developing costs and reduce turnaround times. Individual rolls of undeveloped film are spliced together to form large rolls of film for batch processing. As the film is processed, a notcher locates the exposed frames and notches an edge of the film near each detected frame. Printing equipment uses the notches to position each frame before printing the frames on photographic paper. Prior to redelivery of the processed film to the customer, the film is cut into strips. A film cutter senses the notches as a means of positioning the film to the proper cut location. As the film advances through the cutter, the notches are counted. After a predetermined number of notches has been sensed, the film has been advanced an appropriate distance so that, ideally, the film cutter cuts the film in the unexposed area between adjacent exposed frames.
One problem associated with automated batch-processing labs is that, if for any reason the notches are not located in proper relation to the exposed frames, the film cutter may cut the film in the wrong location. There are numerous reasons why the notcher might place a notch in a wrong location, including, for example, operator error in setting up and adjusting the notcher or a component failure in the notcher that causes the notcher to be out of calibration. In any event, misplaced notches may cause the film cutter to cut the film through an exposed frame, thereby irretrievably damaging that frame. Obviously, the consequences of such an error are unpleasant and will most likely subject the processing lab to customer complaints and a loss of future business from that customer.
As can be readily appreciated from the foregoing discussion, there is a need in a film-processing operation for preventing a film cutter from cutting film in a predetermined cut location that erroneously lies in an exposed frame. This invention is directed to a method for achieving these results and an apparatus for carrying out the method.